Gear-tooth-rounding machine



Dec, 9, 1924.4

P. s. ARNOLD i GEADR TOOTH-ROUNDING MACHINE Fied April 2, 1950 4 Sheets-Sheet l Dec. 9, 1924.V 1,518,239

P. s. ARNOLD GEAR TOOTH ROUNDING MACHINE Filed April 2, 1920 4 Sheets-Sheet 2 L7/21295 6. HMM/d Dec. 9, 1924. 1,518,239

A P. s. ARNoLD l GEAR TOOTH ROUNDIIING` MACHINE Filed April 2, 1920 4 Sheets-Sheet 4 Patented Dec. 9, 1924.

A; UNITED srAfrEsv PATENT OFFICE.

PHILIP s ARNOLD, or HIGHLAND PAR-x, xIcHIeAN, AssIGNon To HILTON o. ences,

" or DETROIT, HICHIGAN.

emTooTH-MUNDTNG HAQHINF.

applicati@ med pnl 2,

To all whom. t may coowem."

Be it know that I, PHILrP S. ARNOLD, a citizen of the United States, residing at Highland Park, county of Wayne, State of Michigan, have invented a certain new and useful Improvement in Gear-Tooth-Rounding Machines, and declare the following to be a full, clear, and exact description of the `same, such as will enable others skilled in lthe artto which it pertains t` make and use the same, reference being had to the accompanyi'ng drawings, which form a part of this specific-ation.

This invention relates to gear tooth roundn ing machines, and its object is to provide a simple and eiiicient mechanismfor rounding the ends of the teeth of spur gears for use in sliding gear transmission of automotive vehicles where theI gears are moved on their longitudinal axes into mesh one with the l other. The principal object of this invention is to provide a`cutterofa chisel like form, the cutting edge of which is moved inr a semi-circular path to shear or plane the l tooth end on one side at a single stroke, the gear being held stationary during the cutting operation. A further feature of the invention'is to provide two shearingcutters of the character stated simultaneously operable ,and each operating upon a gear tooth f of the respective gear.` The construction one side only of the end of a. gear tooth cutting substantially from an axial line passing centrally through the tooth between the sides thereof and cutting out throu h one side thereof on a circular path. As t e two cutters are turned in the same direction one cutting on the left hand side of a gear tooth and the other on the righthand side, the

gear that is first cut by one cutter, after the 4 finishing of the cuttin operations on the several teeth, may be p aced in position to,

be operated upon by the other cutter which completes the rounding of .the end of the tooth. An additional object of this invention is to provide a machine having a plurality of cutters as described to increase the output of the machine and thus lesseningthe cost of operation. A further object ofthe invention isv to provide'means for holding a gear in fixed axial position relative tothe and ndexin mao. sgml N0. $70,357.

ctter and nieans for indexing the gear by t ming it on its axis during the recovery of the cutter for a subsequent operation and to fixedlly hold the gear during the/cutting period. Another obJectof this invention is to provide a shearing tool or cutter oscillatable. through an arc about the end of a gear tooth and means for varyin the position of the gear whereby the cui? of the tooth 4 may be made to occupy a plane at an angle to the horizontal permitting the tooth to, be rounded on an axis at an angle to the' plane of the said endof the tooth thus causing the4 rounded tooth to slope inwardly from the side of the gear. Other novel features ofthe invention are found in the mechanism for operating the cutters and in the mechanism for regulating the indexing device for indexing gears having teeth-of' various sizes. These and other objects and novel features of the invention are hereinafter more fully Y described and claimed and the referred 75 form of construction embodying the invention is shown in the accompanying drawin in which-- ig. 1 is a vertical section of a gearV tooth rounding machine embodying my invention showing the principal operating parts of the machine.

Fig. 2 is a vdetail showing the cam and gear and'rack for oscillating the cutters. and arrangement of the cutters andthe gears is such that each cutter operates on` f Fig) 3 is a detail of themechanism for 85 actuating the indexing fingers.

Fig. 4 is a section taken through the supporting table for the gear on line 4-4 of ig. 5 is detail in plan view showing a 00 mechanism in the position for holding t e gear rigid during the cutting operation. n

Fig. 6 1s a similar fview showing the mf dexing mechanism when set in position to index the Fig. 7 is a detail in the indexing iin rs.

Fig. '8 is a etailv in perspective ofthe other of the indexing lingers.

Fig. 9 is a section taken on lline '9-9 of perspective of one of IFig. 5 showing in deta-ilthe means used to vary the extent of movement of the indexin bar.

igs. views showing the opera-tion, offthe cutter 10, 11,' 12 and 13 are diagrammatic 105 and holder. y

The machine in its preferred form consists. of a central frame member 1 on o posite vertical sides of which are provide the tables 2 and 3 riding in vertical ways 4 and 5 respectively on the said sides of the frame. These tables are independently controlled by means of a shaft 6 in each case having a gear 7 vthereon meshing with the-bevel gear 8 on the vertical screw shaft 9 threaded in a, box 10 supported or provided on the base 11 of the frame 1. The-shaft 6 and the upper end 12 of the screw 'shaft are supported in bear-V ings provided in each table therefor and rotation of either shaft 6 in one directlon or the other raises or lowers thel respective table.

The tables are alike as shown and each has provided on the u per end thereof ways l3and. a..block 14. from Fig. 4, the table at the upper end has a slot 15 therein between the ways 13 in which a lug 16 from the member 14 depehds. This lug is threaded to receive a screw shaft ,17 provided at the outer end wit .a hand wheel 18 and by rotation of the and wheel and shaft the block l14 may lbe moved on the Ways 13 provided therefor. To this block 14 in each/case is pivotally sup orted at the forward end the block 19 havlng 'thereon a spindle 20 for centrally supportin -the .gear 21 to be operated on. The'spin le 20 is held by .a bolt 22 having a. head positioned in a T slot 23 therefor provided inthe block 19 whereby the spinldle may be set .in different positions as required to .receive gears of various diameters and position the same relative to the cutting tool 24. The gear is roughly positioned by means of the spindle 20 and bolt 22vand by means of the screw shaft 17 isbrought to acclirate position relative to the tool and indexing mechanism for the gear hereinafter described. c

` Each tool 24 is carried in a holder 25 as will be understood from Figsl and 14, and the 4two v tools are attached to opposite ends res etively of an oscillatible lshaft 26 carri in bearings provided at the upper end of the central framework 1. It is to be noted that the cutting-end of thetool 24 is vof chisel like form and is so positioned relative to the center/of oscillation of the shaft 26 as to `cut about the end of the gear tooth on one'side only, the extended center of osnism hereinafter described the cillation passin throu h the tooth preferably substantia y equi istantl from o posite sidesjthereof 'as will be un erstood rom Fig. 10. By meansof anindexing mechatoot may be presented to the tool in' such rmanner that the axisof oscillation 0f tlm,- tOOl passes s will be understoodnearer to one side of the tooth than the other which is desirable in some cases and with this character of tool the material is cut from the' tooth at one stroke of the tool which cutsthe corner therefrom rounding one side of the tooth at vone end and the plane of movement of the tool is at a right angle to the plane occupied by the gear when the ear is in horizontal position as shown in ig.,1. Preferably, the tool is of such shape that the tooth is cut back at the pcripheryto a greater extent than at the point of connection with the body of the gear so that the end of the tooth occupies a plane at an angle to the side of the gear and this maybe increased on decreased by tiltin of the holder or block 19 for the gear whic 1 may be set at various angles to the horizontal as'indicated by dotted lines at the right side of Fig. 1. A convenientmeans `for tilting the table or holder 19 is b means of a slotted arcuate plate 27 attac red to the.

member 19 and having graduation marks 28 on one side which by reading in relation to a. mark 29 on the member 14 determining the angle at which the block 19 and conscquently 'the face of the'gear 21 is held. A screw .member 30 is provided extending through the arcuate slot of the member 27 by means of which it is securedin place. Other mechanism, however, for adjusting the angular relationship of the members 19 and 14 maybe employed if desired.

L As before stated, t e tool is of the type used i-n a planer and is chisel like in form being moved about the end of the gea-r tooth on an axis passing through the ear tooth adjacent one end. EvidentlyV tie mechanism must be o'f sufficient strength to permit the shaving or cutting of the material at one stroke of the cutter and, for this purpose, I have provided the cutter shaft 26 with a gear 31 with which meshes a rack 32 movable vertically in the frame member 1 which is rovided witha support 33 for the rack ormed in the casting. The rack at the lower end is provided with a roller 34 ridin on a cam 35 attached to the driving sha. t 36 extending in arallel relation with the gear shaft 26. is cam 35 is shown more artcularl in Fig. 2 and turns in the direction" shown y the arrow in said figure'. The sha of the cam isr such as to gradually. raise t e rack 32 to the full extent land thereupon to permit the rack to fall rapidly to original position whereby a quick return of the tool is secured. As the tool is freed from the'work, upon completion of its cutting movement, the rack will return to normal position by gravity and return the tool to posit-ion for, a succeeding eut on a succeeding tooth b reason of the opera-tive tools each operating upon a gear at the same interval, there being one gear 21 on one side of the machine and a gear 21 upon the opposite side of the machine positioned for operation by the res tive cut ers. It is to' be noted, however, t t the too in operating on the gear 21 cuts only the left hand side of the endlof the ar tooth and, while the cutter 24 isl in suc ition that the cutter 24a rounds the right nd corner of the end y of a gear tooth and thus a gear to completely round the end of the tooth must be `operated upon by both cutters in the manner here stated. In operating upon a ear the said gear is first placedeupon one o they spindles 20 where one side of the end`of each gear tooth `is rounded and this gear is Vthen placed upon the opposite side for opera-tion by the cutter 24aand a new gear placed upon the s indle 20 at the right side of the machine. hus lat each oscillation of ther shaft 26 and cutting tools the work completed is equivalent to the roundin completely of the end of one tooth and t e outpgut of the machine is thus increased in that in ei'ect a complete rounding of the/ e d of y the ycutters through the tooth is occasioned by an oscillation of Substantially one-fourth of an arc of a circle.

The indexing mechanism is shown in Figs.

'5 to 1'3. As shown in Fig. 5 this mechanism f consists of a bar 40 reciprocable in bearings on ways provided at the upper end of the frame 1 on each side beneathreach cutter. The reciprocation of the bar 40 is vtransversel of the axis of oscillation of the shaft 26. n thisbar 40 is 'a pawl 41 provided with a spring 42 tending to hold the same outward into engagement with the lteeth of the gear 21 shown in Jrelation.` thereto in Fig. 5.y The forward end .of the pawl is shaped to correspond to the shape of the side of a ear teoth andb movement to the left of Fig. 5 vwill turn t e gear b reason of the engagement of the said en with a side of the tooth. The pawl end is further shaped so that on movement to the right of Fig. 5 the pawl end will draw out from between the teeth and drop 4into the space between succeeding teeth. A second pawl 43 is provided pivoted toan ear 44 secured to the head of the frame 1 and thus the pawl 43 is stationarily pivoted relative to the bar 40 while the pawl 41 is pivoted directly on the bar 40 and moves with it. The bar has an upwardly extending lug 45 thereon which rides along ythe gear side of the pawl 43 during movement of the rod 40. f The pawl 43 is provided with a cain like projection 46. that is adaptedv to be engaged by this lug 45 on movement of the rod 40 to the right of the position shown in Fig. 5 and the contact of.this.,lug 45 with the cam like rojection 46 of the pawl- 43 raisesT the paw 43 from engagement with thefgear. As the pawl 43 will be understood' lfrom the drawing. This is stationarilyepivoted the end of the pawl i.

' the teeth of the gear the pawl 43 is raised.

On completion of movement of the rod 40 to the right of Fig. 5 the pawl 41 will drop p into position between the next succeedin teeth of the gear while the pawl 43 is sti|` held out of engagement therewith by reason of the lug 45 riding along the face of the pawl. Then, on movement to the left occa-f sioned by mechanism next described, thel pawl 41 turns the gear on its spindle and, as the lug 45 rides out from under the cam 46, the end of the awl 43 drops into place. The relationship ci) mechanism is such that, after the pawl 43 drops into place, the cut-v ting tool 1s operated to cut upon the tooth held between the opposed ends of the pawls v41 and 43 and the' gear is thus rigidly held in position durin this cutting operation. These pawls 41 an 43 are 'below'and out of the path of movement of theA cutters.

The bar 40 is reciprocated'by means of what I have termed a cam bar 50, there being such a bar for each side of the machine as bar is provided with a. roller 51 at the lower end riding on the cam 52 provided therefor on the shaft 36. The upper end of the ibar 50 is formed with anan lar cam face 53 and the ba' terminates in a compara- /tively narrow portion 54, which, when the bar 40 is at the'right of the position shown in Fi'g. 5, is engaged by the roller 55 provided on the end of the bar 40. A spring 456 of considerable tensionis provided tending to move the bar 40 tothe right of the position shown in Fig. 1 and thus hold the roller continuously in engagement with'the side of the cam bar 50. Thus, when the roller'is at the right of the position in Fig. 5 with the pawl 41 dropping into position between the teeth in the space indicated at 57, the`roller is racticall in contact withc this portion 54 o? the cam ar. Asis shown in Fig. 3 the cam 52 on which the roller 51 rides is shaped to cause an upward moveido ment of the bar50 and consequent move-` downward movement of the rack 32. The

cam 52 for the caln' bar 50 has a portion 60 rac'tically a true circle which holds the cam r with the widest portion engaged by the roller .55 of the ban 40, and thls position is maintained during the Vcutting operation caused by the upward movement of the rack 32. By this relationship of the operation of the cutters and indexing mechanism the ar is turned forward to bring a succee 'n tooth to position for operation as the too retreats toloriginal position. This is graphcally illustrated in the di to 13. In Fig. 10 the tool 24 for instance,

1 sin the posi-tion.:at the beginning ofa cut which is to be taken along the dotted lines shownin Fig. 10 on the tooth 1. In Fig. 11 the completion of this movement of the cutting tool is shown, the gear having been held stationarily in position as will be understood by therelative position of the tooth 1 of Fig. 10 and. the same tooth directly therebeneath inFig. 11. On the completion of this movement of the cutter, as before described, the indexing mechanism starts to operate turning the tooth 1 tothe right as shown by the arrow in Fig. 12 and during; movement of the tool 24 inthe direction shown by the arrow in the said figure, so that upon completion of the return movement of the cutters the tooth 2 of the gear will occupy the position relative to 'the tool that was originally occupied bythe tooth 1 as is indica-ted in Fig. 13 whereupon the cutter is again operated.'

It is therefore to be seen and understood that the gear is held rigidly by the pawls 41 and 43 durin the period the cutting tool is operating an at the finish of the cutting movement is positioned between the two adjacent teeth as shown in Fig. 11. After the is brought to cutting cutting tool begins to retreat to assume its original 'position the gear is moved at a speed corresponding to the speed of movement of the tool and as the tool is raised from between the adjacent teeth from the position shown in Fig. 12 Ito the position shown in Fig. 13 the next succeeding tooth position. The speed of rotation of the gear in the indexing movement is determined by the shape of the cam 52 and cam face 53 of the bar 50 so that the gear at the same speed practically as the speed of movement of the bar 40 movles t e movement ofthe cutter in retreating. vThe position of the cam 35 shown in Flg. 2 is practically the position Vof the parts at the finish of the cutting operation of the tool and the face 70 of the said cam is shaped to permit a fairly quick movement of the tool in returning to original position. The face 71 of the cam 52 is the ortion traversed by the roller 51 in raising t e cam bar 50 to move the bar 40 to index the gear during the time the portion 70 of the cam 35 permits ythe retreating movement of the cutter, the

relationship of the two cams being approxllmately shown in Figs. 2 and 3. 4 By changing the angle of the face 53 of the bar 50 a more `or ess rapid movement of the'bar 40 is occasioned by the cam 52. However, to permit the same bar 50 to be utilized inthe indexing of the gears of vari-` which is provided with agrams Figs. 1()l ous sizes of teeth I have provided an adjustable ,stop device 75 carried ves 76 and 77 in op site faces enga by ribs 78 on the part 5. Y This stop is substantially U shaped in form and is pxrovided with a binding screw 79 to fix t e same in position. This stop as will be understood from Fig.

ontherod40' 5, 'determines the extent of movement off the bar 40 under action of its spring 56'and thus the bar 40 when released to action by its spring by withdrawal of the bar 50 may move to the right only the distance permitted by this stop 75. Thus the roller 55 may stop short of contact with the face 80 at the end 54 of the bar 50 and thus on movement of the bar 50 upward the roller 55 will not be actuated untll a rtion ofthe angular face 53 has passed a ve the adjacent, face of the roller 55. Movement of the bar 40 may thus be delayed and the extent of its movement from one position tothe other decreased and thereby permitting a greater or less length of movement of the bar 40 as may be determined by the distance between the centers of the teetli of the gear vto be operated upon. By this arran ment described of the sto device, a bar 50 avng a face 53 of a'spei c an le and cam 52 of a specific actuating face 1 may be utilized withk gears of considerable diierence in distance between centers of \teeth and the indexin mechanism is the fore adapted for use with a great variety f ars.

To recapitulate, the sev ra objects of the invention as is evidenced from the above description are secured by the construction'Y descri ed herein or equivalent mechanism and thus a gear tooth rounding device is provided in whichl the gear is axially ixed relative to the tool and is indexed biiturning about the iixed axis during the i le movement ofy the tool in retreatin for a succeedration and is indexe or turned at a 1n o pe'ipiiaral speed corresponding to thespd of retreat of the tool and thus no loss of time is occasioned as is usual in devices of this character where the indexing interval occurs subsequent to the retreat of the tooljto its iginal cutting position. Further, by operating upon two gears at the same time one cutter operating upon the end of the tooth on one side and the other cutter operating upon the other side, the end of a tooth is completely rounded Jin a turn of the cutting tool throu han are of practically ningty de ees and t us a-tooth 1s both round an indexed within the period of time required for the cutting tool to traverse an arc ofone hundred and eighty degrees and the saving in time on this'machine is ual to that required in other devices'to in ex the gear.

' It is further to be observed that the mechanism is simple, inexpensive in construction and eicient in operation.

^ arc of substantially ninet degrees of a circle and then successively su mitting the'oppo- L site side of the ends of the teeth to a second and similar shearing operation.

2. In a machine for1 rounding the end of a -i gear tooth, a cutter Aof 'chisel like form,

upeans for indexing the means for oscillating the cutter, means for positioning the gearwith the end of `atooth 1n suclnposition that'the cutter shears the same from the center of the said end to the side on an" arc of substantially ninet' degrees of acircle, and means for fixedly old` lng the gear during the cutting operation.

3. In a machine for rounding the end of a gear tooth, a .shearing cutter oscillatable through an are substantially of ninety'de grecs of a circle, means for positioning the gear with ,a tooth thereof ,in `such relation that a-side of one end of the tooth is sheared or cut on an arc, means for holding the 'gear stationary during the cutting operation, and.v gearon the return movement. of thefcutter. 1

4. In a machine for rounding the ends of gear teeth, ashearingfcutter adaptedto be oscillated through an arc, means for positioning a gear with a tooth thereof in the path of movement \of the tool to shear one side of an end of a tooth, and a second cutter simultaneously operable with the first cutter adapted to operate' upon the opposite side of a tooth of a gear to complete the rounding of the tooth ends.

5s In`a machine for rounding the ends of gear teeth, a cuttingtool of chlsel like form and operation adapted to be turned through an are, mechanism for holding a gear with the tooth thereof -in such position that t e axis of movement of the tool passes throug the tooth substantially equidistantly1 between the sides, and means for turning the tool to shear the side of one end of the tooth |on an arc. Y i I Gf In a machine for rounding the ends of agees' tooth, a cutting tool of chisel like form and operation a pted to be turned through an arc of a circle, mechanism for] holding a gear. with the end of the tooth thereof in such-position that a radial line 'passing through the tooth equidistantly be-A tween-'sides thereof coincides withtheaxis of movement of the tool, means for turning the tool to shear the sidefofone end of the tooth, said means being adapted to return the tool for a subsequent o eration and i means for indexing the gear' uring the re-` turn movement of the tool,

' l 7 In a machine for rounding the ends of I gear teeth, a cutting tool of chisel like form adapted to be o scillatedv through an arc of a circle, mechanism for holding a gear' with the end of a tooth thereof in such position means for holding a second gear in the same relative position to the second cutter as the first gear is to the first cutter whereby the oscillation of the shaft cuts one side of the end of the tooth on one gear and the opposite side of the end of the tooth of the other gear, and means for indexing the gears to bring succeeding teeth to position for a subsequent operation.

8. In a machine for roundin the ends of i gear teeth, a` cutting tool of c hlsel like form adapted to be oscillated through an arc of substantially ninety degrees, means for sitioning a gear with the end of a tooth t ereof in positlon whereby the cutting movement of Athe cutter shears one side of the end of the tooth on the desired radius, and a second cutter simultaneously o rable with ,the rst cutter operating upon e opposite side of a tooth of a second gear positioned in similar relation thereto as the first gea-r relative to its cutter. f

l9. Ina machine for rounding the ends of gear teeth, a pair Qf cutting tools, a shaft the tools being secured to opposite ends o the shaft and both facing in the same direction, means for oscillatingthe--shaft through an arc substantially of ninety degrees, and vmeans for positioning a vtool at opposite ends o the shaft whereby the teeth of the two gears are operated upon simultaneously, and indexing mechanism for each gear adapted to index the same during the idle movement of the cutters.

10. In a machine for rounding the ends of gear teeth, a cutting' tool of chisel like form adapted to be oscillated in avert-ical plane 'through an are of substantially ninety degrees, means for positionin a ear with a tooth thereof in such relatlon t at the extended axis of oscillation passes through ,the tooth adjacent the end thereof substantiallyV centrally between opposite sides, means for holding the gear stationary during the cutting operation, and means for positioning the gear with the ends of the teeth vin a plane at an 'angle to the axis of oscillation of the cutter. v

11. In a gear-tooth rounding machine, an oscillatable cutter of chisel like form adapted to be turned in a vertical plane through an arc of substantially ninety degrees, means yfor itioning a gear relative vthereto in faxial yv fixed relation, means for "positioning the side of the -gear and end of the tooth to b'e operated upon in planes at various angles ar relative to each to the Aplane of movement of the tool with with the side of gear teeth, a cutting the extended axis of oscillation passin through the tooth to be operated upon a vjacent one end, and means forv turning the gear on its axis to index the same.

12. In a machine for rounding the-ends of gear teeth, a cutting tool of chisel like form adapted to be turned about an axis, means for positioning a gear with` the face thereof parallel to the plane of movement of the tool, means for turning the tool throu h an arc of substantially ninety degrees, t e tool passin frpm position substantially parallel wit the plana of the end of the tooth to a position substantially parallel the tooth'and between adjacent teeth, and means for indexin the gear during the return of the tool to original position and thereby positioning the adjacent tooth for the cutting operation.

13. In a machine for rounding' the ends of tool adapted to ,turn about an axis to shear the side of an end of a tooth on anJ arc substantially of ninety degrees, an adjustable table for the gear to position the same witha tooth thereof in such position that the axis of oscillation of the tool passes through the tooth adjacent one end, a holder for the tool of a character to maintain the same in axially fixed relation to the tool, means for varying the langle of the side of the ear relative to the plane of oscillation of `t e tool, and an indexing mechanism fon turning the gear subsequent to each cutting operation.

14. In a machine for rounding the ends of gear teeth, a cutting tool adapted to be turned about an axis to shear the side of an end of a tooth on'an arc, a second cutting tool operable in the same manner, means for positioning a gear cutter that the axis of oscillation-of the cutter passes through a tooth substantiall equidistantly between sides thereof, the teet being cut on opposite sides b the respective cutters, a table for each of t e gears, means for adjusting the table to position the gear at the proper height, an adjustable ho der for each gear whereby the said gear may be positioned toward or from the toolg, the said holders bein further angularly adjustable relative to teplane of oscillation of the tools, and indexin mechanism for each gear operable during t e idle movement of the respective tools, said indexing mechanism being of a character to hold the gear rigidly during the cutting operation and to turn the same on its axis uri .1g the indexing movement.

15. In a machine for roundin the ends of gear teeth,- 'a shearing cutter a a ted to be oscillated through an arc of su tantially ninety degrees, means for' ositioning a gear -in axially iixed relation with the cutter and with a tooth thereof in such position that the `pivoted thereto in such relation to eachv axis of oscillation of the cutter p through vthe tooth adjacent one end, an indexing mechanism for indexing the gear, said mechanism comprisin a reciprocable bar, a pawl aving an end adapted to engage between teeth of the gear, a second pawl in pivotally ixed relation to the axis of the. gar and having an end adapted to engage pawls being so positioned that adjacent ends thereof engage opposite 'sides of a tooth to hold he same during the cutting operation, vmeans for moving the bar to position the first pawl back of a succeeding tooth adjacent the one`operated on, means whereby the said movement of thebar raises the second pawl from engagement with the gear, and means for varying the extent of movementof the bar to osition the first pawl whereby gears of di erent pitches may be operated upon, and mechanism for moving the bar in the opposite direction to turn the, gear yby the first pawl and substantially on completion of .the movement to release the second pawl to engage the opposite side of the tooth engaged b the' irst pawl.

16. The method o roundin the ends of gear teeth. which consists in su mitting each tooth end to the operation of a shearin cutter to cut from the center of said tooth end to the side thereof and submitting the gear teeth to a second cutter of similar character to cut from the said center of the end of the gear to the opposite side to complete the roundin of the teeth.

A 17. The metho of rounding the ends of gear teeth which consists in submitting the side of an end of each tooth in succession to the operation of a shearing cutter roundin one edge of said end on an arc and then su jecting the gear to a succeeding similar shearin operation rounding the opposite edges o the teeth in succession.

` 18. In a machine for roundin the end of a gear tooth, a cutter of chisel 1i e form and operation adapted to be turned on an axis passing angle, means for relatively varying the angle of the axes of the gear and cutter, and means for positioning a gear with the end of a tooth in position for the cutting operation. l 19. In a; machine for f rounding the ends of gear teeth, and operation adapted to be turned through an arc whose axis passes through the axis of the gear at an angle, means for turning the cutter, and means for positioning a gear with an end of a tooth for the cutting o eration to round the edge on one side o the tooth end and a second cutter of practically identical operation and relationship actuated simultaneously with the first cutter adapted to cut the opposite edges of the tooth ends of a gear first submitted to the first cutter.

through the axis of the gear at an' a cutter of chisel like form l 20. In a machine for rounding the ends of gear teeth, a pair of cutters both of chisel cutters being such that one of the cutters 10 like form tand operation adapted to be operates upon one side of the end of a gear simultaneously turned in the same direction tooth and the other cutter operates upon the lthrough an arc, means adjacent each cutter respective` opposite side of the gear tooth 5 for supporting a gear in axially fixed rewhereby in eiect each operation of the lation to the respective cutters, means for cutters completely rounds a single tooth end. 15 holding the gear for the cutting operation, `In testimony whereof, `I sign this speciand means for simultaneously indexing the ication. gears, the relationship of the gears and i PHILIP S. ARNOLD. 

